EXAMPLES. 1. COMMON SALT. The pure salt is gently ignited. a. Estimation of the chlorine from 0. 5 to 1 gramme if the salt is dissolved in water, and the solution is acidified with nitric acid and precipitated with nitrate of silver. (§ 107. I. a.) b. Estimation of the soda. About one gramme of the salt is dissolved in water, and subsequently converted into sulphate of soda by evaporation with sulphuric acid. (§ 72. 1.) (For the calculated percentage composition, I refer to the " corrections" at the end of the work.) 2. CRYSTALLIZED CARBONATE OF SODA. The pure noneffloresced salt is finely powdered, and subsequently repeatedly pressed between sheets of blotting paper, fresh sheets being used every time, (§ 14. a.) a. Estimation of the water, (1-2 grammes). The salt is cautiously ignited, (§ 17. a.) b. Estimation of the carbonic acid, (residue of a, or 1-2 grammes). The salt is decomposed by means of sulphuric acid, and the carbonic acid determined by the loss of weight which the decomposed salt suffers in the process, (§ 105. II. b. ß. aa.) (For the calculated percentage composition I refer to the "corrections" at the end of the work. 3. CARBONATE OF LIME. The carbonate of lime is gently ignited. a. Estimation of the lime. About 1 gramme of the carbonate is dissolved in hydrochloric acid, and the solution is supersaturated with ammonia, and subsequently precipitated with oxalate of ammonia, (§ 76. 2. b.) b. Estimation of the carbonic acid. About one gramme of the carbonate is ignited with borax glass. (§ 105. II. b. a.) 4. CHLORIDE OF BARIUM. The pure salt is gently ignited. a. Estimation of the barytes. chloride is dissolved in water, and precipitated with sulphuric acid. (§ 74. 1. a.) Ba.. About one gramme of the the solution is subsequently 5. CRYSTALLIZED SULPHATE OF MAGNESIA. The salt is levigated and dried according to the directions of § 14. b. a. Estimation of the crystallization water. This is effected by drying 1.5 to 2 grammes of the salt, at from 266° to 284° F. b. Estimation of the basic water. The residue of a. is gently ignited. c. Estimation of the sulphuric acid. From one to two grammes of the salt are dissolved in water, some hydrochloric acid is added to the solution, and subsequently chloride of barium. (§ 100. I.) d. Estimation of the magnesia. From one to two grammes of the salt are dissolved in water, sal ammoniac is added to the solution, and subsequently ammonia, and the mixture is finally precipitated with phosphate of soda. (§ 77. 2.) The salt is powdered and dried at 212. (§ 14. d.) 16.68 32.36 7.28 43.68 100.00 Estimation of the potass. From 1.5 to 2 grammes of the salt are ignited, and the residue is extracted with solution of sal ammoniac; the solution is evaporated to dryness, and the residue subsequently ignited. (§ 71.) The levigated salt is dried in the water-bath. From one to two grammes of the salt are dissolved in water; the chromic acid is then reduced by means of hydrochloric acid and alcohol, and the solution is finally precipitated with ammonia. (§ 99. I. a.) 8. CRYSTALLIZED SULPHATE OF COPPER. The finely-powdered salt is pressed repeatedly between blottingpaper. (§ 14. a.) a. Estimation of the crystallization water. From 1 to 1.5 gramme of the salt is dried in the water-bath. (§ 14. d.) b. Estimation of the basic water. The residue of a is heated in a crucible over a spirit-lamp until the whole of the water present is expelled; a very high temperature, however, is to be carefully avoided. c. Determination of the oxide of copper. About 1.5 gramme of the salt is dissolved in water; the solution is boiled, and precipitated boiling with potass. (§ 90. 1. a.) 9. ACETATE of lead. Large noneffloresced crystals should be used; they are to be finely powdered, and the powder subsequently repeatedly pressed between blotting-paper, fresh paper being used every time. (§ 14. a.) Estimation of the lead. a. One gramme of the salt is dissolved in water, and the solution subsequently precipitated with carbonate of ammonia. (§ 87. 1.) b. A portion of 1 to 1.5 gramme of the salt is ignited in a porcelain dish, and the residue is subsequently treated with acetic acid, etc. (§ 87. 4.) From 0.5 to 0.8 gramme of pure oxide of antimony is dissolved in hydrochloric acid, and some tartaric acid added to the solution, which is then diluted with water, and subsequently precipitated with sulphuretted hydrogen. (§ 95. 1.) 11. PERCHLORIDE OF MERCURY. Pure perchloride of mercury, perfectly soluble in water, should be selected, and about one gramme used to separate the mercury in the dry way according to the method described at § 89. 1. a. 12. ANALYSIS OF PHOSPHATE OF SODA. Pure and recently crystallized phosphate of soda is powdered, and the powder pressed repeatedly between blotting-paper, fresh paper being used every time. This is effected by a. Estimation of the crystallization water. drying the salt first at 212° F., and finally in the air or oil bath at about 572° F. (§ 14. d.) b. Estimation of the basic water. This is effected by igniting the residue of a. c. Estimation of the phosphoric acid. A portion of about 1.5 gramme of the salt is dissolved in water, and sal ammoniac added to the solution; the fluid is subsequently precipitated by sulphate of magnesia with ammonia. (§ 101. I. b.) d. Estimation of the soda. The filtrate of c. is treated according to the instructions given at § 101. II., a., B. 14. ALKALIMETRICAL EXAMINATIONS according to FRESENIUS and WILL, (§ 136.) In both experiments (13 and 14) the student has to analyse, in the first place, recently ignited pure carbonate of soda, since this will afford him the means of controlling the results of the subsequent analysis of commercial specimens of soda. 15. ACIDIMETRICAL METHODS, (§ 112. I. b.) Two experiments are to be made with unequal portions of one and the same acid, since this will enable the student to control the results. 16. EXAMINATION of peroxide of MANGANESE, (§ 125.) Every sort is to be analysed twice. 17. EXAMINATION OF CHLORIDE OF LIME. One and the same sort is analysed by every one of the three methods described at § 137. N N |